This invention concerns a component to a lubricating composition that imparts improved resistance to oxidation and corrosion. Specifically the component, 1-[Di(4-octylphenyl)aminomethyl]tolutriazole dissolved in 40-60% mineral oil has difficulty maintaining its liquid character over time, and has a short storage stability. This makes it difficult to handle when preparing lubricant additive blends and lubricant compositions.
The 1-[alkyl diphenyl)aminomethyl]tolutriazole or benzotriazole compounds are prepared in a known manner from tolutriazole or benzotriazole (or mixtures thereof), formaldehyde and alkylated diphenylamine by means of the Mannich reaction. These variations are described in U.S. Pat. No. 6,184,262, which is hereby incorporated by reference. The benzotriazole derivatives of formula I
wherein R′ and R″ are independently selected from hydrogen or lower alkyl, R1-R4 are independently selected from alkyl having up to 11 carbon atoms or phenylalkyl, or mixtures thereof. Tolutriazole designates a benzotriazole compound which is methylated in the benzene ring in the 4-position and/or 5-position. Therefore, the derivative is designated “benzotriazole derivative”.
The component, 1-[Di(4-octylphenyl)aminomethyl]tolutriazole, (formula II) is a well-known antioxidant and corrosion inhibitor. In U.S. Pat. Nos. 4,880,551 and 6,743,759 it was reported that 1-[Di(4-octylphenyl)aminomethyl]tolutriazole acts as an antioxidant synergist with methylenebis(di-nburtyldithiocarbamate) and also with phenols.

Lubricating oils, greases and similar oleaginous materials are used under conditions which contribute to their breakdown during normal service. The severe high temperature operating conditions of modern engines accelerate deterioration of lubricants due to oxidation. Oxidative deterioration is accompanied by formation of gum, sludge and acids which may cause corrosion of the engine as well as chemical breakdown of the lubricant.
Surprisingly, it has been found that the addition of a polyacrylate polymer during the reaction to produce the 1-[Di(4-octylphenyl)aminomethyl]tolutriazole in a mineral oil diluent has been instrumental in keeping the product in solution for an extended period, longer than the mere addition of the polyacrylate polymer to the product after the reaction. This polyacrylate polymer is added at an amount between about 0.1 and about 5%, preferably about 0.2 to about 2.0%, and most preferably at about 0.5 to about 1.0% to the total weight of the reaction mixture. The polyacrylate polymer itself is a solution that typically contains between 25 and 75% polyacrylate polymer in oil.